EP3253293A2 - Procédés, systèmes, appareils et programmes informatiques pour enlever des artefacts d'un ensemble de données de tomosynthèse - Google Patents

Procédés, systèmes, appareils et programmes informatiques pour enlever des artefacts d'un ensemble de données de tomosynthèse

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Publication number
EP3253293A2
EP3253293A2 EP16706144.9A EP16706144A EP3253293A2 EP 3253293 A2 EP3253293 A2 EP 3253293A2 EP 16706144 A EP16706144 A EP 16706144A EP 3253293 A2 EP3253293 A2 EP 3253293A2
Authority
EP
European Patent Office
Prior art keywords
marker
alignment marker
projection images
ray
tomosynthesis
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP16706144.9A
Other languages
German (de)
English (en)
Other versions
EP3253293B1 (fr
Inventor
Fred DUEWER
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Sirona Dental Systems GmbH
Sirona Dental Inc
Original Assignee
Sirona Dental Systems GmbH
Sirona Dental Inc
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Filing date
Publication date
Application filed by Sirona Dental Systems GmbH, Sirona Dental Inc filed Critical Sirona Dental Systems GmbH
Publication of EP3253293A2 publication Critical patent/EP3253293A2/fr
Application granted granted Critical
Publication of EP3253293B1 publication Critical patent/EP3253293B1/fr
Active legal-status Critical Current
Anticipated expiration legal-status Critical

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Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
    • A61B6/02—Arrangements for diagnosis sequentially in different planes; Stereoscopic radiation diagnosis
    • A61B6/025—Tomosynthesis
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
    • A61B6/02—Arrangements for diagnosis sequentially in different planes; Stereoscopic radiation diagnosis
    • A61B6/027—Arrangements for diagnosis sequentially in different planes; Stereoscopic radiation diagnosis characterised by the use of a particular data acquisition trajectory, e.g. helical or spiral
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
    • A61B6/50—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment specially adapted for specific body parts; specially adapted for specific clinical applications
    • A61B6/51—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment specially adapted for specific body parts; specially adapted for specific clinical applications for dentistry
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
    • A61B6/52—Devices using data or image processing specially adapted for radiation diagnosis
    • A61B6/5211—Devices using data or image processing specially adapted for radiation diagnosis involving processing of medical diagnostic data
    • A61B6/5252—Devices using data or image processing specially adapted for radiation diagnosis involving processing of medical diagnostic data removing objects from field of view, e.g. removing patient table from a CT image
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
    • A61B6/52—Devices using data or image processing specially adapted for radiation diagnosis
    • A61B6/5258—Devices using data or image processing specially adapted for radiation diagnosis involving detection or reduction of artifacts or noise
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
    • A61B6/58—Testing, adjusting or calibrating thereof
    • A61B6/582—Calibration
    • A61B6/583—Calibration using calibration phantoms
    • A61B6/584—Calibration using calibration phantoms determining position of components of the apparatus or device using images of the phantom
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B90/00—Instruments, implements or accessories specially adapted for surgery or diagnosis and not covered by any of the groups A61B1/00 - A61B50/00, e.g. for luxation treatment or for protecting wound edges
    • A61B90/39—Markers, e.g. radio-opaque or breast lesions markers
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T11/00—2D [Two Dimensional] image generation
    • G06T11/003—Reconstruction from projections, e.g. tomography
    • G06T11/008—Specific post-processing after tomographic reconstruction, e.g. voxelisation, metal artifact correction
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T5/00—Image enhancement or restoration
    • G06T5/50—Image enhancement or restoration using two or more images, e.g. averaging or subtraction
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T5/00—Image enhancement or restoration
    • G06T5/77—Retouching; Inpainting; Scratch removal
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T7/00—Image analysis
    • G06T7/30—Determination of transform parameters for the alignment of images, i.e. image registration
    • G06T7/33—Determination of transform parameters for the alignment of images, i.e. image registration using feature-based methods
    • G06T7/337—Determination of transform parameters for the alignment of images, i.e. image registration using feature-based methods involving reference images or patches
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B90/00—Instruments, implements or accessories specially adapted for surgery or diagnosis and not covered by any of the groups A61B1/00 - A61B50/00, e.g. for luxation treatment or for protecting wound edges
    • A61B90/39—Markers, e.g. radio-opaque or breast lesions markers
    • A61B2090/3966—Radiopaque markers visible in an X-ray image
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
    • A61B6/50—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment specially adapted for specific body parts; specially adapted for specific clinical applications
    • A61B6/51—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment specially adapted for specific body parts; specially adapted for specific clinical applications for dentistry
    • A61B6/512—Intraoral means
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T2207/00—Indexing scheme for image analysis or image enhancement
    • G06T2207/10—Image acquisition modality
    • G06T2207/10116—X-ray image
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T2207/00—Indexing scheme for image analysis or image enhancement
    • G06T2207/30—Subject of image; Context of image processing
    • G06T2207/30004—Biomedical image processing
    • G06T2207/30036—Dental; Teeth
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T2207/00—Indexing scheme for image analysis or image enhancement
    • G06T2207/30—Subject of image; Context of image processing
    • G06T2207/30204—Marker

Definitions

  • the present application relates generally to obtaining tomographic images in a dental environment, and, more particularly, to methods, systems, apparatuses, and computer programs for removing artifacts from a tomosynthesis da- taset . Description of related art
  • X-ray radiography can be performed by positioning an x-ray source on one side of an object (e.g., a patient or a portion thereof) and causing the x-ray source to emit x- rays through the object and toward an x-ray detector (e.g., radiographic film, an electronic digital detector, or a photostimulable phosphor plate) located on the other side of the object.
  • an x-ray detector e.g., radiographic film, an electronic digital detector, or a photostimulable phosphor plate
  • the x-rays As the x-rays pass through the object from the x-ray source, the x-rays are transmitted to varying degrees depending on the composition of the object and the energy of the x-rays, and x-rays arriving at the x-ray detector form a two-dimensional (2D) x-ray image (also known as a radiograph) based on the cumulative x-ray attenuation through the object.
  • 2D two-dimensional
  • X-ray radiography can be performed in dentistry, and dental x-ray radiography systems typically include an x-ray source suspended from a wall-mounted arm and an intraoral x-ray sensor.
  • Dental x-ray radiography systems are relatively compact and conveniently can be used chair-side to provide guidance during a treatment, such as an endodontic procedure.
  • dental x-ray radiography also does not 5 provide depth information concerning a patient's unique internal anatomical features (e.g., the shape of dental root structures) , although such depth information often would be useful in diagnosing and treating dental pathologies.
  • X-ray computed tomography CT
  • CBCT cone beam computed tomography
  • CT computed tomography
  • CBCT cone beam computed tomography
  • dental CBCT is performed by rotating an x-ray source and an x-ray detector with a large field of view (typically, at least large enough to image a patient's com- 15 plete jaw) through a scan angle of at least 180° around a patient's head, while the patient is sitting or standing in the machine.
  • the 3D data acquired by CBCT can be presented on a display screen for clinician review as a 3D rendering or as a stack of parallel 2D tomographic image slices, each 20 slice representing a cross-section of the patient's anatomy at a specified depth.
  • CBCT machines carry a high cost of ownership, are too large for use in chair-side imaging and expose patients to a relatively high dose of x- rays (due to the large field of view, the at least 180° 25 scan angle, and the penetration of x-rays through the complete jaw) .
  • Tomosynthesis is an emerging imaging modality that provides 3D information about a patient in the form of 2D tomographic image slices reconstructed from projection im- 30 ages taken of the patient with an x-ray source from multiple perspectives within a scan angle smaller than that of CBCT (e.g., ⁇ 20°, compared with at least 180° in CBCT).
  • Tomosynthesis systems are commercially available for mammo- graphic imaging.
  • Tomosynthesis as an imaging modality can also be applied to intraoral imaging.
  • Tomosynthesis image slices are reconstructed by pro- cessing the projection images taken in a model of the geometry of the tomosynthesis system (e.g., the relative position and angle of the imaged object in 3D space) .
  • Spatial instability in the geometry of the tomosynthesis system and/or the object can result in misaligned projection imag- es that deviate from the aforementioned model, which, in turn, can degrade the quality and spatial resolution of the reconstructed tomosynthesis image slices.
  • spatial instability in intraoral tomosynthesis imaging can arise from motion, whether intentional or unintentional, of the patient, the arm-mounted source, and/or the intraoral detector .
  • Projection images affected by motion or other spatial instabilities can be aligned prior to reconstruction so as to compensate for such motion or instability.
  • One so- lution is adapted from CBCT imaging to tomosynthesis imaging, namely, placing radiopaque markers within the field of view of the tomosynthesis imaging system, which create visible guides in the projection images that can facilitate realignment of the projection images.
  • CBCT imaging to tomosynthesis imaging namely, placing radiopaque markers within the field of view of the tomosynthesis imaging system, which create visible guides in the projection images that can facilitate realignment of the projection images.
  • three or more highly attenuating marker particles of a known geometry can be placed within the field of view of the imaging system to allow for simple computation of a sample position for a fixed x-ray source and a fixed detector geometry.
  • intraoral tomosynthe- sis is typically smaller than that of CBCT, it can be difficult to place the radiopaque markers in a location that does not obscure relevant anatomical detail in the projec- tion images.
  • an intraoral sensor is generally restricted to a usable projection angle of ⁇ 45 degrees.
  • objects are typically significantly blurred along the depth directions.
  • intraoral sensors must be small enough to fit inside a subject's mouth, the radiopaque markers tend to obscure relevant dental anatomy wherever the markers are placed.
  • the high contrast edges of radiopaque markers in the projection images can result in major recon- struction artifacts (e.g., out-of-plane contributions and in-plane ringing) in the tomosynthesis images.
  • major recon- struction artifacts e.g., out-of-plane contributions and in-plane ringing
  • the use of highly attenuating marker particles can result in image artifacts, which are typically characterized by strong streaking throughout the imaged volume due to large image gradients being back- projected through the volume, as well as dimming of imaged features that are obscured by the marker particles.
  • image artifacts are generally benign because any artifacts generated by the marker particles will typically only obscure a small fraction of the imaged volume.
  • Another solution is to align the projection images based on inherent details and features of the projection images, which is also known as markerless alignment, in contrast to the above-mentioned technique of using radiopaque markers as artificial alignment landmarks.
  • the accuracy of markerless alignment is typically limited by the extent in depth of the image features used for alignment.
  • Certain types of imaged anatomy, such as teeth and trabeculae, may contain large, irregular features that are not conducive to markerless alignment.
  • a method, system, apparatus, and computer program product are provided for removing marker artifacts from a tomosynthesis da- taset.
  • a first plurality of projection images are acquired by tomosynthesis x-ray imaging, the first plurality of projection images containing at least one imaged representation of at least one alignment marker.
  • the imaged representation of the at least one alignment marker on the first plurality of projection images is minimized to generate a second plurality of projection images.
  • a plurality of tomographic images are reconstructed from the second plurality of projection images.
  • the method can be useful for reliable, artifact-free alignment of projection images, which thereby improves the data quality and spatial resolution of reconstructed tomosynthesis images.
  • FIG. 1A is a system block diagram of a tomosynthesis system according to one example embodiment herein.
  • FIG. IB illustrates an example of a linear scan path used by the tomosynthesis system according to an example embodiment herein.
  • FIG. 1C illustrates an example of a curved scan path used by the tomosynthesis system according to an example embodiment herein.
  • FIG. ID illustrates an example of a circular scan path used by the tomosynthesis system according to an exam- pie embodiment herein.
  • FIG. IE illustrates an example of shadow casting from an orthogonal projection angle.
  • FIG. IF illustrates an example of shadow casting from a non-orthogonal projection angle and the parallax in- cuted in the image of the objects.
  • FIG. 2 illustrates a block diagram of an example computer system of the tomosynthesis system shown in FIG. 1A.
  • FIG. 3 is a flowchart illustrating a process for ac- quiring a tomosynthesis dataset and removing marker artifacts therein according to an example embodiment herein.
  • FIG. 4A illustrates a front elevation view of an example aiming ring with markers disposed thereon.
  • FIG. 4B illustrates a top view of the example aiming ring of FIG. 4A.
  • FIG. 5 illustrates an example projection image that includes an image of a marker.
  • FIG. 6 illustrates the example projection image of FIG. 5 with the marker image removed.
  • Different ones of the Figures may have at least some reference numerals that are the same in order to identify the same components, although a detailed description of each such component may not be provided below with respect to each Figure.
  • Fig. 1A illustrates a block diagram of an intraoral tomosynthesis system 100 for obtaining an intraoral tomosynthesis dataset, and which is constructed and operated in accordance with at least one example embodiment herein.
  • the system 100 can be operated to obtain one or more x-ray images of an object 50 of interest, which may further include one or more sub-obj ect ( s ) 52.
  • object 50 may be a tooth (or teeth) and surrounding dentition of a patient
  • sub-obj ect ( s ) 52 may be root structures within the tooth.
  • the system 100 includes an x-ray detector 102 and an x-ray subsystem 116, both of which, including subcomponents thereof, are electrically coupled to a computer system 106.
  • the x-ray subsystem 116 hangs from a ceil- ing- or wall-mounted mechanical arm (not shown) , so as to be freely positioned relative to an object 50.
  • the x-ray subsystem 116 further includes an x-ray source 104 mounted on a motorized stage 118 and also shows an on-board motor controller 120.
  • the on-board motor controller 120 controls the motion of the motorized stage 118.
  • the computer system 106 is electrically coupled to a display unit 108 and an input unit 114.
  • the display unit 108 can be an output and/or input user interface.
  • the x-ray detector 102 is positioned on one side of the object 50 and the receiving surface of the x-ray detec- tor 102 extends in an x-y plane in a Cartesian coordinate system.
  • the x-ray detector 102 can be a small intraoral x- ray sensor that includes, for example, a complementary metal-oxide semiconductor (CMOS) digital detector array of pixels, a charge-coupled device (CCD) digital detector ar- ray of pixels, or the like.
  • CMOS complementary metal-oxide semiconductor
  • CCD charge-coupled device
  • the size of the x-ray detector 102 varies according to the type of patient to whom object 50 belongs, and more particularly, the x-ray detector 102 may be one of a standard size employed in the dental industry.
  • Examples of the standard dental sizes include a "Size-2” detector, which is approximately 27 x 37 mm in size and is typically used on adult patients, a “Size-1” detector, which is approximately 21 x 31 mm in size and is typically used on patients who are smaller than Size-2 adult patients, and a “Size-0" de- tector, which is approximately 20 x 26 mm in size and is typically used on pediatric patients.
  • a "Size-2" detector which is approximately 27 x 37 mm in size and is typically used on adult patients
  • a “Size-1” detector which is approximately 21 x 31 mm in size and is typically used on patients who are smaller than Size-2 adult patients
  • a "Size-0" de- tector which is approximately 20 x 26 mm in size and is typically used on pediatric patients.
  • each pixel of the x-ray detector 102 has a pixel width of 15 ⁇ , and correspondingly, the Size-2 detector has approximately 4 million pixels in a 1700 x 2400 pixel array, the Size-1 detector has approximately 2.7 million pixels in a 1300 x 2000 pixel array, and the Size-0 detector has approximately 1.9 million pixels in a 1200 x 1600 pixel array.
  • the color resolution of the x-ray detector 102 may be, in one example embodiment herein, a 12-bit grayscale resolution, although this example is not limiting, and other example color resolutions may include an 8- bit grayscale resolution, a 14-bit grayscale resolution, and a 16-bit grayscale resolution.
  • the x-ray source 104 is positioned on an opposite side of the object 50 from the x-ray detector 102.
  • the x- ray source 104 emits x-rays 110 which pass through object 50 and are detected by the x-ray detector 102.
  • the x-ray source 104 is oriented so as to emit x-rays 110 towards the receiving surface of the x-ray detector 102 in at least the z-axis direction of the Cartesian coordinate system, where the z-axis is orthogonal to the x-y plane associated with the receiving surface of the x-ray detector 102.
  • the x-ray source 104 can also emit x-rays 110 while positioned at each of multiple different locations within a scan angle 112, where a 0° position in the scan angle 112 corresponds to the position for emitting x-rays
  • the user initially positions the x-ray subsystem 116, and hence, also the x-ray source 104, to a predetermined starting position relative to the object 50.
  • the computer system 106 controls the on-board motor controller 120 to move the x-ray source 104 via the motorized stage 118, based on the known starting position, to step through each of the different locations within the scan angle 112.
  • the computer system 106 controls the x-ray source 104 to cause the source 104 to emit x-rays 110 at each of those locations.
  • the axis of the x-ray source 104 is positioned for each location so that the extension of the source axis sub- stantially intersects at an aiming point 122 close to or on the center of the intraoral sensor in the x-y-z Cartesian coordinate system defined by the detector, as discussed above.
  • the aiming point 122 may be, for example, located close to the detector such that x-rays 110 emitted from the x-ray source 104 positioned at the outer limits of the scan angle 112 are aimed at and do not miss the x-ray detector 102.
  • the 0° position is represented in x-ray source 104, while reference numerals 104a and 104b repre- sent the same x-ray source but in two other example positions within the scan angle 112.
  • the scan angle 112 can be, for example, ⁇ 20° from the 0° position, although this example is not limiting.
  • the positioning of x-ray source 104 along the scan angle 112 may form different scan paths, such as, for example, a linear scan 130 shown in Fig. IB, a curved scan 132 shown in Fig. 1C, or a circular scan 134 shown in Fig. ID.
  • the linear scan 130 Fig. IB
  • the x- ray source 104 moves linearly in an x-y plane while emit- ting x-rays 110 toward the aiming point 122.
  • the x-ray source 104 moves in an arc while emitting x-rays 110 toward the aiming point 122.
  • the x-ray source 104 rotates around the z-axis while emitting x-rays 110 toward the aiming point 122.
  • the scan positions also may be arranged in any particular one or more planes of the Cartesian coordinate system.
  • x-rays 110 As emitted x-rays 110 pass through the object 50, photons of x-rays 110 will be more highly attenuated by high density structures of the object 50, such as calcium- rich teeth and bone, and less attenuated by soft tissues, such as gum and cheek.
  • One or more of the attenuating structures can be sub-obj ect ( s ) 52.
  • X-rays 110 passing through and attenuated by object 50 (and sub-obj ect ( s ) 52) are projected onto x-ray detector 102, which converts the x-rays 110 into electrical signals and provides the elec- trical signals to computer system 106.
  • the x-ray detector 102 may be an indirect type of detector (e.g., a scintillator x-ray detector) that first converts x-rays 110 into an optical image and then converts the optical image into the electrical signals, and in an- other example embodiment, the x-ray detector 102 may be a direct type of detector (e.g., a semiconductor x-ray detector) that converts x-rays 110 directly into electrical signals.
  • the computer system 106 processes the electrical signals to form a two-dimensional projection image of the ob- ject 50 in a known manner.
  • the image size of the two-dimensional projection image corresponds to the dimensions and the number of pixels of the x-ray detector 102. Accordingly, pixel values of the two-dimensional projection image represent the cumulative x-ray attenuation through the object 50.
  • the system 100 can collect a plurality of projection images by first positioning the x-ray source 104 at different angles in scan angle 112, which may include the 0° position, and emitting x-rays 110 at each of those different angles through object 50 towards x-ray detector 102, which, in conjunction with computer system 106, outputs a corresponding projection image for each of the different angles.
  • the plurality of projection images may include a total of fifty-one projections: one orthogonal projection image, obtained when the x-ray source is at the 0° position, and fifty projection images, each obtained when the x-ray source 104 is positioned at different angles within a range of + 20° from the z-axis (corresponding to the scan angle 112) .
  • the number of projection images may range from twelve to seventy. Because the orthogonal projection image is obtained when the x-ray source is at the 0° position, the orthogonal projection image has the same appearance as a conventional x-ray image. That is, the two-dimensional orthogonal projection image has no depth perception, and one or more sub-obj ect ( s ) 52 within object 50 may appear overlaid one on top of another in the orthogonal projection image, as represented in Fig. IE, for example.
  • sub-obj ect ( s ) 52 at different depths of the z-axis within object 50 undergo varying degrees of parallax when imaged from different angles along the scan angle 112, as represented in Fig. IF, for example.
  • the x-ray source 104 should be aimed relative to the x-ray sensor 102 such that the full receiving surface of the x-ray sensor 102 is exposed to x-rays 110 emitted by the x-ray source 104 as the x-ray source 104 is swept through the scan angle 112. If the x-ray source 104 is not properly aimed, a part of the x-ray sensor 102 may be left unexposed to x-rays 110 at one or more positions of the x- ray source 104 in the scan angle 112, and the corresponding projection image will appear clear (i.e., white) and devoid of sub-obj ect ( s ) 52 in the unexposed region.
  • an extraoral aiming ring 124 is attached to x- ray sensor 102 to provide a target such that, when x-ray source 104 is at the 0° position, the emitted x-rays 110 are aimed at the center of the x-ray sensor 102 and also are substantially orthogonal to the x-ray sensor 102.
  • the aiming ring 124 includes an aperture 125 and at least one marker 126 disposed within the aperture 125, as illustrated in the example of Fig. 4A. In this embodiment, the at least one marker 126 is provided on at least one attachment surface 127 provided within the aperture 125 of the aiming ring 124.
  • Two attachment surfaces 127 can be provided that each include the at least one marker 126.
  • the two attachment surfaces 127 can be affixed to oppo- site sides of the aiming ring 124.
  • the tomosynthesis system 100 collects the plurality of projection images, as described above, the at least one marker 126 is also imaged by x-rays 110 and thus appears on the plurality of projection images.
  • the presence of the at least one marker 126 on the plurality of projection images facilitates, in a manner described further herein below, alignment of the plurality of projection images prior to reconstruction into a stack of tomosynthesis images.
  • the aiming ring 124 may be attached to a sensor holder 128 that is adapted to hold the x-ray sensor 102.
  • the at least one marker 126 can be affixed to the aiming ring 124 approximately two inches from the x-ray sensor 102 by, for example, the positioning of the sensor holder 128.
  • three separated, non-collinear markers 126 are provided, such that the three markers 126 are visible in each scanned image.
  • markers 126 traverse across the field of view, additional markers may be necessary to ensure that each image projec- tion has a sufficient number of markers.
  • thirty markers 126 are affixed to the aiming ring, with at least eight markers 126 visible in the field of view of the x-ray sensor 102.
  • the shape and the x-ray attenuation coefficient of the markers 126 are predetermined, and can be stored in the computer system 106 in one example embodiment herein.
  • the markers 126 may be designed to provide sharp edges for a wide angular range.
  • the shape of the markers 126 should be considered, such that sharp edges are provided.
  • the marker attenuation should be sufficiently large, so as to be at least comparable in magnitude with the larger edges of the edges of the image projections upon which the markers are overlaid .
  • the shape of the marker (s) 126 can be selected from a number of different types, including, for example, spheres (and more particularly, in one example embodiment herein, spheres having a diameter of 100 ⁇ ) , near- spherical shapes, non-spherical shapes, a periodic structure, and a non-periodic structure.
  • spheres and more particularly, in one example embodiment herein, spheres having a diameter of 100 ⁇
  • spherical or near-spherical particles are used in or- der to provide the sharp edges needed to effectively locate the markers in a series of image projections, as discussed above.
  • the size of the markers should be considered, given that the use of smaller markers has been found to be beneficial, as it may be possible to minimize artifact creation with the smaller markers, assuming that the markers are localized.
  • a marker 126 is provided that maximizes the ratio of the marker's thickness gradient to the total scanned volume.
  • the marker provided should have a projected shape that does not vary over a broad range of viewing angles.
  • the projected shape of the marker does not vary over a broad range of viewing angles; however, the thickness gradient of a spherical marker is low, except at the edges of the sphere.
  • a hollow, spherical marker is provided, given that the total volume of the marker's attenuating material remains low, while the thickness gradient remains high.
  • the spherical material for the marker should be sufficiently transmis- sive, to allow for generally unaffected viewing through the center of the spherical marker, and to mimic the x-ray absorption of the bone material being imaged, such that the attenuation contribution of the spherical marker can be effectively removed.
  • the diameter of the spherical marker should be selected so that the projection of the marker does not overlap with itself on consecutive image projections. In one example embodiment, assuming that the spherical marker is separated from the x-ray sensor 102 by at least 50 mm, and that the tomosynthesis system 100 changes a scan angle 112 by one
  • each marker 126 can be constructed to have an x-ray attenuation coefficient that is similar to dental anatomy.
  • the at least one marker 126 can be constructed from steel, aluminum, or any metal or metal alloy that has an energy-dependent x-ray attenuation coefficient similar to bone, and a thinness sufficient to fall within the dynamic range of the tomosynthesis system.
  • a calibrated pro- jection thickness can be calculated for each projection image. Using this calibrated projection thickness, the contribution of the marker 126 can be determined and accurately subtracted, once the marker (s) 126 is located in the image, as discussed in more detail below.
  • the image contrast and image quality of the region superimposed under the at least one marker 126 is substantially maintained.
  • each marker 126 can be constructed as a sphere having a high x-ray attenuating exterior (such as an electroplated radiopaque metal) and a low x-ray attenuating interior (i.e., a radio- lucent material) .
  • a high x-ray attenuating exterior such as an electroplated radiopaque metal
  • a low x-ray attenuating interior i.e., a radio- lucent material
  • x-rays 110 passing through a marker 126 having a low x-ray attenuating interior will experience less overall attenuation than x-rays 110 passing through a marker 126 constructed entirely from a radiopaque material.
  • the computer system 106 aligns the plurality of projection images based on the representation of the markers appearing in the images, minimizes the presence of the markers on the aligned projection images, and processes the plurality of projection images to reconstruct a series of two-dimensional tomosynthesis image slices, also known as a tomosynthesis stack of images, in a manner to be described below.
  • Each image slice is parallel to the plane in which the receiving surface of the x-ray detector 102 extends and at different depths of the z-axis.
  • One or more image slices of the tomosynthesis stack are provided by the computer system 106 for display to the user on the display unit 108.
  • FIG. 3 shows a flow diagram of a process according to an example embodiment herein for performing tomosynthesis imaging and removing artifacts from a tomosynthesis dataset.
  • Step S304 a calibration function that can translate measured x-ray attenuation to object thickness and vice versa, and that is specific to the tomosynthesis system 100, is generated.
  • the calibration function is generated as follows. First, an x-ray phantom (not shown) having a known x-ray attenuation characteristic is placed between the x-ray sensor 102 and the x-ray source 104.
  • the known x-ray attenuation characteristic of the x-ray phantom will be a cumulative x-ray attenuation through the x-ray phantom, which can be calcu- lated by the Beer-Lambert Law (also known as Beer' s Law) from a known thickness of the x-ray phantom and a known x- ray attenuation coefficient of the x-ray phantom.
  • Beer-Lambert Law also known as Beer' s Law
  • the x-ray attenuation character- istic of the x-ray phantom may be measured.
  • the expected transmission may be calculated by integrating over all energies emitted by the source as:
  • an imaging operation is performed by emitting x-rays 110 from the x-ray source 104 toward the x-ray sensor 102, which converts the received x-rays 110 into electrical signals that are processed by the computer system 106 to form a projection image.
  • the calibration function is then generated by correlating the pixel values of the pro- jection image (which represent the cumulative attenuation of the x-rays 110 through the x-ray phantom) with the known x-ray attenuation characteristic of the x-ray phantom.
  • Step S304 is performed every time the procedure of Fig. 3 is performed.
  • Step S304 is optional, that is, Step S304 need not be performed every time the procedure of Fig. 3 is performed, but instead, can be performed periodically (e.g., weekly, monthly, annually, or at other intervals), at irregular intervals, or as ne- cessitated by a change in performance of the x-ray sensor
  • Step S306 the computer system 106 uses an in- verse of the calibration function to calculate an estimated x-ray attenuation expected to be attributable to an alignment marker 126 appearing in an image acquired by the tomosynthesis system 100, such as in the plurality of projection images acquired in Step S308 described further herein below.
  • the alignment marker 126 has a known geometry and a known x-ray attenuation coefficient, as described above. Accordingly, the estimated x-ray attenuation and corresponding estimated pixel values are calculated by applying the known geometry and known x- ray attenuation coefficient of the marker 126 to the calibration function generated in Step S304.
  • the projection images correspond to an equivalent material thickness.
  • the marker model may be calculated as the projection through the solid model of the marker, scaled by the ratio of the attenuation lengths of the marker material to the attenuation length in bone.
  • a measure roughly corre- sponding to thickness may be computed by estimating the negative logarithm of the ratio of the transmitted flux to the transmitted flux when no sample is present.
  • the marker thickness may be approximated by fitting the region occupied by the marker to a function with spatial dependence identical to the projection through the solid model of the marker and thereby determining a scaling factor.
  • the scaling factor is then combined with the projection through the solid model of the marker to obtain a marker model suitable for subtraction.
  • the tomosynthesis system 100 is prepared by a user for performing an imaging procedure by manually aiming the x-ray source 104 towards an extraoral aiming ring 124 attached to the x-ray sensor 102, in the manner described above (e.g., aligned so as to avoid cone cut), in one example embodiment herein.
  • the user also verifies that at least one marker 126 disposed on the aiming ring 124 is within the field of view of the x-ray sensor 102.
  • Step S308 the intraoral tomosynthesis system 100 acquires a plurality of projection images of object 50 and the at least one marker 126 located within the field of view of the x-ray sensor 102, over a scan angle 112 (which may be predetermined), in the manner described above.
  • the x-ray source 104 is moved by the motorized stage 118 and control circuitry 116 to different positions within the scan angle 112, and the computer system 106 controls the x-ray source 104 to emit x-rays 110 at each posi- tion.
  • x-ray source 104 is scanned while rotating to project x-rays towards the detector at each location from -20° from the z-axis to +20° from the z-axis in evenly distributed increments of 0.8° to pro- vide 51 scan angles, including the 0° position, although this example is not limiting.
  • the x-rays 110 then pass through and are attenuated by the object 50 and the at least one marker 126 before being projected onto the x-ray detector 102.
  • the x-ray detector 102 converts the x-rays 110 into electrical signals (either directly or indirectly, as described above) and provides the electrical signals to the computer system 106.
  • the computer system 106 processes the electrical signals collected at each scan angle position to acquire the plurality of projection images, each image comprising an array of pixels.
  • the image acquired with the x-ray source 104 at the 0° position is also referred to herein as an orthogonal projection image .
  • each projection image includes an image representation of the imaged object 50 (e.g., a patient's teeth) and an image representation of the at least one marker 126 (referred to hereafter as a "marker image" for convenience).
  • each projection image includes more than one marker image.
  • Fig. 5 illus- trates an example projection image acquired according to
  • Step S308 showing teeth 402 and a marker image 404.
  • Fig. 6 illustrates the example projection image of Fig. 5 with the marker image 404 removed, such that area 502 is clear of the marker image 404.
  • the color depth of each pixel value of the projection images may be 12-bit grayscale, and the dimensions of the projection images cor- respond to the standard dental size of the x-ray detector 102, as described above.
  • a Size-2 detector may produce projection images that are approximately 1700 x 2400 pixels in size
  • a Size-l detector may produce projec- tion images that are approximately 1300 x 2000 pixels in size
  • a Size-0 detector may produce projection images that are approximately 1200 x 1600 pixels in size.
  • Step S310 the computer system 106 locates the marker images in each of the plurality of projection imag- es.
  • the corresponding marker image is circular in shape, and the marker images can be located in a known manner by, for example, a circular Hough transform.
  • a known diameter of the marker 126 can be used to locate the marker using, for example, the circular Hough transform (see e.g., Comparative study of Hough Transform methods for circle finding, Yuen et al, Image and Vision Computing, Feb. 1990, or Generalizing the Hough transform to detect arbitrary shapes, D. H. Ballard, Pattern Recognition (1981)).
  • Step S312 the computer system 106 aligns each of the plurality of projection images relative to one another based on the marker images appearing in the plurality of projection images (e.g., marker 404 shown in Fig. 5).
  • the slices are aligned by performing image registration of corresponding marker images in respective projection images according to a known manner (e.g., linear transformations, which may include rotation, scaling, translation, and the like) .
  • the backproj ection matrices used in the later reconstruction process at Step S316 described further herein below can be adjusted to correct for the misalignment of the image slices.
  • Each backproj ection matrix is a function of the position of the x-ray source in relation to the detector.
  • the marker positions may be used to estimate the deviation of the x-ray source position from the planned trajectory for a given projection and thereby used to adjust the input parameters used to calculate the backproj ection matrix applied to that projection.
  • Step S314 is performed to remove or at least substantially minimize the marker images from the plurality of projection images to generate a plurality of marker- minimized projection images.
  • Fig. 6 illustrates an example of a projection image in which the marker image 404 of the projection image of Fig. 5 has been re- moved, such that an area 502 is clear of the marker image 404.
  • a reason for removing the marker images is that their presence (and in particular, high contrast edges that can be attributed to the marker images) may contribute to reconstruction artifacts such as out-of-plane contributions and in-plane ringing in the tomosynthesis image slices reconstructed from the plurality of projection images in Step S316, which is described further herein below.
  • Step S314 can be performed according to different techniques, which will now be described in turn.
  • Step S314 is performed by subtracting the estimated marker x-ray attenuation calculated in Step S306 from each of the marker images located in Step S310. Because the pixel values of a marker image represent a cumulative attenuation of x-rays through a corresponding marker 126 and through any portion of object 50 in the path of those x-rays, subtracting the estimated marker x-ray attenuation from the projection images leaves, as a remainder, the x-ray attenuation that is primarily attributable to the object 50.
  • Step S314 image information about the object 50 (e.g., dental anatomy) that was obscured by the marker images can be revealed.
  • the marker 126 must first be located in the scanned image (s), such that the contribution of the marker 126 to the x-ray attenuation in the image content can be removed.
  • the center of the spherical marker will have a high attenuation contribution, but a low attenuation gradient.
  • the attenuation contribution of the spherical marker towards the center of the spherical marker can be removed by direct subtraction of a linearized attenuation.
  • the edges of the spherical marker will also have a high attenuation gradient, and the details of this attenuation gradient will depend on the subpixel displacement of the spherical marker. Accordingly, in this em- bodiment, exact removal of the attenuation gradient contributed by the edges of the spherical particle can be challenging .
  • Step S314 is performed by an in-painting technique (instead of the above-described subtraction technique) , which defines, for each marker image located in Step S310, a region slightly larger than the marker image and assigns new pixel values to the projection images in those regions.
  • the in-painting technique is computationally simpler than the subtraction technique, but it typically does not preserve image information about the object 50 that was obscured by the marker images.
  • Many different in-painting techniques are possible, including, for example, textural in-painting, interpolating techniques, curvature-based in-painting, or landmark-based in- painting.
  • a textural in-painting technique is used. Such a technique is appropriate for qualitative imaging where the esthetic quality of the reconstructed portion of the projection image is of primary importance. For example, in CBCT imaging, in-painting tech- niques that result in a smooth match between an obscured portion of a projection image and the surrounding portions are preferred. Thus, a textural in-painting might be preferred in this type of example embodiment.
  • an in-painting technique is utilized that interpolates inwardly from a specified-boundar- -in a projection image using Laplace's equation. This type of interpolating technique has the advantage of generating a smooth region.
  • an in-painting technique that uses interpolating has the disadvantage of generating inaccurate re- suits for features with spatial extents that are smaller than the region being reconstructed.
  • a curvature-based in-painting technique can be used.
  • a curvature-based in-painting technique can provide good results for simple objects that are partially obscured in a projection image, such as, for example, the edge of a tooth overlaid by a marker particle.
  • a landmark-based in-painting technique is used.
  • additional known image information can be used, such as, for example, other images in a tomosynthesis series, in order to estimate data missing from a single image being reconstructed.
  • Step S316 the computer system 106 processes the plurality of marker-minimized projection images generated in Step S314 using a reconstruction technique in order to reconstruct a series of two-dimensional tomosynthesis image slices (also known as a stack of tomosynthesis image slices) and may also perform deblurring and other image enhancements, as will be described further herein.
  • a reconstruction technique in order to reconstruct a series of two-dimensional tomosynthesis image slices (also known as a stack of tomosynthesis image slices) and may also perform deblurring and other image enhancements, as will be described further herein.
  • Each reconstructed image slice is a tomographic section of object 50 comprising an array of pixels, that is, each image slice represents a cross-section of object 50 that is parallel to the x-y plane in which the receiving surface of the x-ray detector 102 extends, has a slice thickness along the z- axis, and is positioned at a different, respective location along the z-axis than other image slices.
  • the slice thick- ness is a function of the reconstruction technique and aspects of the geometry of the system 100, including, primarily, the scan angle 112.
  • each image slice may have a slice thickness of 0.5 mm by virtue of the geometry of the system 100 and the reconstruction technique.
  • the de- sired location of each reconstructed image slice along the z-axis is provided as an input to the reconstruction performed in Step S316 either as a pre-programmed parameter in computer system 106 or by user input via input unit 114 and/or display unit 108.
  • the computer sys- tern 106 can be instructed to reconstruct, from the plurality of projection images, a first image slice that is one millimeter (1 mm) away from the surface of x-ray detector 102 along the z-axis, a last image slice being at fifteen millimeters (15 mm) away from the surface of the x-ray detector 102, and image slices between the first image slice and the last image slice at regular increments along the z- axis of two-hundred micrometers (200 ⁇ ) , for a total of seventy-one image slices.
  • the sample position is fixed relative to the x-ray detector 102.
  • the sample position can be fixed by, for example, using an apparatus that rigidly holds the x-ray detector 102 in position, including, for example, a bite-block that is clamped between the teeth when an intraoral scan is being conducted.
  • the system geometry can be determined using alignment markers 126
  • the back-projection matrices can be modified according to the known system geometry, and used to compute back- projected volumes that can then be added together to reconstruct the sampled volume.
  • Reconstruction of the tomosynthesis image slices in Step S316 may be performed in accordance with any existing or later developed reconstruction technique.
  • reconstruction of the tomosynthesis image slices in Step S316 utilizes a shift-and-add technique, such as that described in the publication by D. G. Grant, entitled “Tomosynthesis: A Three-Dimensional Radiographic Imaging Technique", IEEE Transactions on Biomedical Engineering, Volume 19, 1972, pp. 20-28, and also described in the review publication by J. T. Dobbins et al., entitled “Digital X-ray Tomosynthesis: Current State of the Art and Clinical Potential", Physics in Medicine and Biology, Volume 48, 2003, pp. R65-R106 (the J. T.
  • the shift- and-add technique utilizes information about the depth of sub-object (s) 52 along the z-axis that is reflected in the parallax captured by the plurality of projection images, as described above.
  • an image slice is reconstructed by first spatially shifting each projection image by an amount that is geometrically related to the distance between the image slice and the aiming point 122 along the z-axis.
  • the shifted projection images are then averaged together to result in the image slice, where all sub-objects 52 in the plane of the image slice are in focus and sub-objects 52 outside of that plane are out of focus and blurry. This shift-and-add process is repeated for each image slice to be reconstructed.
  • the projection images are averaged together without first shifting because sub- objects 52 are already in focus for that plane.
  • a deblurring technique that substantially reduces or removes blurry, out-of-plane sub-objects from an image slice can be performed in conjunction with the reconstruction technique (whether shift-and-add or another technique) .
  • Examples of deblurring techniques that can be employed are described in the J. T. Dobbins et al. publication at pp.
  • R81-R90 and include, for example, spatial frequency filtering, ectomogra- phy, filtered backproj ection, selective plane removal, iterative restoration, and matrix inversion tomosynthesis, each of which may be used in Step S316 to deblur images reconstructed by the shift-and-add reconstruction technique (or another reconstruction technique, if employed) .
  • Step S316 also can include the computer system 106 performing further automated image enhancements such as, for example, image sharpening, brightness optimization, and/or contrast opti- mization, on each reconstructed (and deblurred, where deblurring is performed) image slice in a known manner.
  • further automated image enhancements such as, for example, image sharpening, brightness optimization, and/or contrast opti- mization
  • Step 318 one or more image slices from the stack of tomosynthesis image slices generated in Step S316 are displayed on the display unit 108. [0071] The process of Fig. 3 ends at Step S320.
  • FIG. 2 shows a block diagram of a computer system 200 that may be employed in accordance with at least some of the example embodiments herein.
  • Fig. 2 shows a block diagram of a computer system 200 that may be employed in accordance with at least some of the example embodiments herein.
  • Fig. 2 illustrates a block diagram of the computer system 200.
  • the computer system 200 includes at least one computer processor 222 (also referred to as a "controller") .
  • the computer processor 222 may include, for example, a central pro- cessing unit, a multiple processing unit, an application- specific integrated circuit ("ASIC") , a field programmable gate array (“FPGA”) , or the like.
  • the processor 222 is connected to a communication infrastructure 224 (e.g., a communications bus, a cross-over bar device, or a network) .
  • a communication infrastructure 224 e.g., a communications bus, a cross-over bar device, or a network
  • the computer system 200 also includes a display interface (or other output interface) 226 that forwards video graphics, text, and other data from the communication infrastructure 224 (or from a frame buffer (not shown) ) for display on a display unit 228 (which, in one example embod- iment, can form or be included in the display unit 108) .
  • a display interface or other output interface
  • 226 forwards video graphics, text, and other data from the communication infrastructure 224 (or from a frame buffer (not shown) ) for display on a display unit 228 (which, in one example embod- iment, can form or be included in the display unit 108) .
  • the display interface 226 can include a video card with a graphics processing unit.
  • the computer system 200 also includes an input unit 230 that can be used by a user of the computer system 200 to send information to the computer processor 222.
  • the input unit 230 can form or be included in the input unit 114.
  • the input unit 230 can include a keyboard device and/or a mouse device or other input device.
  • the display unit 228, the input unit 230, and the computer processor 222 can collectively form a user interface.
  • the input unit 230 and the display unit 228 can be combined, or represent a same user inter- face.
  • a user touching the display unit 228 can cause corresponding signals to be sent from the display unit 228 to the display interface 226, which can forward those signals to a processor such as processor 222, for example.
  • the computer system 200 includes a main memory 232, which preferably is a random access memory (“RAM”), and also may include a secondary memory 234.
  • the secondary memory 234 can include, for example, a hard disk drive 236 and/or a removable-storage drive 238 (e.g., a floppy disk drive, a magnetic tape drive, an optical disk drive, a flash memory drive, and the like) .
  • the removable- storage drive 238 reads from and/or writes to a removable storage unit 240 in a well-known manner.
  • the removable storage unit 240 may be, for example, a floppy disk, a magnetic tape, an optical disk, a flash memory device, and the like, which is written to and read from by the removable- storage drive 238.
  • the removable storage unit 240 can include a non-transitory computer-readable storage medium storing computer-executable software instructions and/or data .
  • the secondary memory 234 can include other computer-readable media storing computer- executable programs or other instructions to be loaded into the computer system 200.
  • Such devices can include a removable storage unit 244 and an interface 242 (e.g., a program cartridge and a cartridge interface similar to those used with video game systems); a removable memory chip (e.g., an erasable programmable read-only memory (“EPROM”) or a programmable read-only memory (“PROM”)) and an associated memory socket; and other removable storage units 244 and interfaces 242 that allow software and data to be trans- ferred from the removable storage unit 244 to other parts of the computer system 200.
  • EPROM erasable programmable read-only memory
  • PROM programmable read-only memory
  • the computer system 200 also can include a communications interface 246 that enables software and data to be transferred between the computer system 200 and external devices.
  • Examples of the communications interface 246 in- elude a modem, a network interface (e.g., an Ethernet card or an IEEE 802.11 wireless LAN interface), a communications port (e.g., a Universal Serial Bus (“USB”) port or a Fire- Wire® port), a Personal Computer Memory Card International Association (“PCMCIA”) interface, and the like.
  • Software and data transferred via the communications interface 246 can be in the form of signals, which can be electronic, electromagnetic, optical or another type of signal that is capable of being transmitted and/or received by the communications interface 246. Signals are provided to the commu- nications interface 246 via a communications path 248
  • the communications path 248 carries signals and can be implemented using wire or cable, fiber optics, a telephone line, a cellular link, a radio-frequency ("RF") link, or the like.
  • the communications interface 246 may be used to transfer software or data or other information between the computer system 200 and a remote server or cloud-based storage (not shown) .
  • One or more computer programs are stored in the main memory 232 and/or the secondary memory 234.
  • the computer programs also can be received via the communications interface 246.
  • the computer programs include computer-executable instructions which, when executed by the computer processor 222, cause the computer system 200 to perform the procedures as de- scribed herein and shown in Fig. 3, for example. Accordingly, the computer programs can control the computer system 106 and other components (e.g., the x-ray detector 102 and the x-ray source 104) of the intraoral tomosynthesis system 100.
  • the software can be stored in a non-transitory computer-readable storage me- dium and loaded into the main memory 232 and/or the secondary memory 234 of the computer system 200 using the removable-storage drive 238, the hard disk drive 236, and/or the communications interface 246.
  • Control logic when executed by the processor 222, causes the computer system 200, and more generally the intraoral tomosynthesis system 100, to perform the procedures described herein.
  • hardware components such as ASICs, FPGAs, and the like, can be used to carry out the functionality described herein. Implementation of such a hardware arrangement so as to perform the functions described herein will be apparent to persons skilled in the relevant art(s) in view of this description. In view of the foregoing description, it can be appreciated that high quality tomosynthesis image slices can be reconstructed from aligned and substantially marker-free projection images .
  • example embodiments described herein are not limited to intraoral tomosynthesis imaging.
  • the example embodiments described herein can be used to perform scans of other anatomical regions.

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Abstract

L'invention concerne un procédé, un système, un appareil et des produits-programmes informatiques pour enlever des artefacts marqueurs d'un ensemble de données de tomosynthèse. Selon le procédé, une première pluralité d'images de projection sont acquises par imagerie par rayons x de tomosynthèse, la première pluralité d'images de projection contenant au moins une représentation imagée d'au moins un marqueur d'alignement. Selon un aspect de l'invention, la représentation imagée du ou des marqueurs d'alignement sur la première pluralité d'images de projection est réduite au minimum pour produire une deuxième pluralité d'images de projection. Selon un autre aspect, une pluralité d'images tomographiques sont reconstruites à partir de la deuxième pluralité d'images de projection.
EP16706144.9A 2015-02-04 2016-02-04 Procédés et systèmes pour enlever des artefacts d'un ensemble de données de tomosynthèse Active EP3253293B1 (fr)

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Families Citing this family (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3682807B1 (fr) * 2014-09-16 2024-07-17 Sirona Dental, Inc. Procédés, systèmes, appareils et programmes informatiques pour le traitement d'images tomographiques
JP6780948B2 (ja) * 2016-03-28 2020-11-04 キヤノンメディカルシステムズ株式会社 Ｘ線ｃｔ装置
US10432907B2 (en) * 2016-07-22 2019-10-01 City University Of Hong Kong Electronic system for creating an image and a method of creating an image
WO2018076109A1 (fr) * 2016-10-24 2018-05-03 Torus Biomedical Solutions Inc. Systèmes et procédés de production de vues radiographiques en stéréo étalonnées en temps réel d'un patient sur une table d'opération
US10631799B2 (en) * 2016-12-07 2020-04-28 Harris Corporation Dental image collection device providing optical alignment features and related system and methods
WO2018204705A1 (fr) * 2017-05-03 2018-11-08 Turner Innovations, Llc. Système d'imagerie tridimensionnelle par rayons x
US20220133249A1 (en) * 2017-05-03 2022-05-05 3Dio, Inc. Three dimensional x-ray imaging system
WO2019040056A1 (fr) 2017-08-23 2019-02-28 Carestream Dental Technology Topco Limited Système de tomosynthèse du côté d'un fauteuil dentaire
US10993689B2 (en) * 2017-08-31 2021-05-04 General Electric Company Method and system for motion assessment and correction in digital breast tomosynthesis
US10772594B2 (en) * 2017-12-11 2020-09-15 Dentsply Sirona Inc. Methods, systems, apparatuses, and computer program products for extending the field of view of a sensor and obtaining a synthetic radiagraph
CN111885954B (zh) * 2018-03-20 2024-05-07 株式会社尼康 图像处理方法、存储介质及眼科装置
US10743822B2 (en) * 2018-06-29 2020-08-18 Carestream Health, Inc. Fiducial marker for geometric calibration of bed-side mobile tomosynthesis system
CN109259779B (zh) * 2018-11-30 2022-06-24 上海联影医疗科技股份有限公司 医学图像的生成方法和医学图像处理系统
CN109363770B (zh) * 2018-12-06 2021-08-10 安徽埃克索医疗机器人有限公司 一种手术导航机器人标志点自动识别定位方法
WO2020185823A1 (fr) * 2019-03-12 2020-09-17 Carestream Dental Llc Collimateurs mobiles et statiques et agencements de source de rayons x pour tomosynthèse intra-orale
DE102020209703A1 (de) * 2020-07-31 2022-02-03 Siemens Healthcare Gmbh Bereitstellen eines 3D-Bilddatensatzes eines Untersuchungsobjekts
US11366983B2 (en) 2020-09-09 2022-06-21 International Business Machines Corporation Study-level multi-view processing system

Family Cites Families (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4991579A (en) * 1987-11-10 1991-02-12 Allen George S Method and apparatus for providing related images over time of a portion of the anatomy using fiducial implants
ES2085885T3 (es) * 1989-11-08 1996-06-16 George S Allen Brazo mecanico para sistema interactivo de cirugia dirigido por imagenes.
US5359637A (en) * 1992-04-28 1994-10-25 Wake Forest University Self-calibrated tomosynthetic, radiographic-imaging system, method, and device
US5848125A (en) * 1997-10-03 1998-12-08 Arnett Facial Reconstruction Courses, Inc. Radiopaque landmark skin markers and method
JP3743594B2 (ja) * 1998-03-11 2006-02-08 株式会社モリタ製作所 Ｃｔ撮影装置
US6118845A (en) * 1998-06-29 2000-09-12 Surgical Navigation Technologies, Inc. System and methods for the reduction and elimination of image artifacts in the calibration of X-ray imagers
US6081577A (en) * 1998-07-24 2000-06-27 Wake Forest University Method and system for creating task-dependent three-dimensional images
US6490475B1 (en) * 2000-04-28 2002-12-03 Ge Medical Systems Global Technology Company, Llc Fluoroscopic tracking and visualization system
US20030072478A1 (en) * 2001-10-12 2003-04-17 Claus Bernhard Erich Hermann Reconstruction method for tomosynthesis
US8768026B2 (en) * 2003-11-26 2014-07-01 Hologic, Inc. X-ray imaging with x-ray markers that provide adjunct information but preserve image quality
US7177390B2 (en) * 2004-03-11 2007-02-13 Trex Enterprises Corp Digital x-ray tomosynthesis system
CA2678962C (fr) * 2007-02-22 2016-08-16 Dentsply International Inc. Dispositif de positionnement radiographique dentaire a code couleur
US9597041B2 (en) * 2007-03-30 2017-03-21 General Electric Company Sequential image acquisition with updating method and system
JP2009225945A (ja) * 2008-03-21 2009-10-08 Fujifilm Corp 放射線長尺撮影における撮影支援装置
CN103635139A (zh) * 2011-07-06 2014-03-12 富士胶片株式会社 X射线成像设备和用于其的校准方法
JP5702236B2 (ja) * 2011-07-06 2015-04-15 富士フイルム株式会社 Ｘ線撮影装置およびそのキャリブレーション方法
JP2013233168A (ja) * 2012-05-02 2013-11-21 Morita Mfg Co Ltd 画像処理装置、ｘ線ｃｔ撮影装置および画像処理方法
US9844324B2 (en) * 2013-03-14 2017-12-19 X-Nav Technologies, LLC Image guided navigation system

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WO2016124667A3 (fr) 2016-10-27
US9872663B2 (en) 2018-01-23
KR20170113570A (ko) 2017-10-12
JP6785776B2 (ja) 2020-11-18
WO2016124667A2 (fr) 2016-08-11
US20160220212A1 (en) 2016-08-04
EP3253293B1 (fr) 2022-06-08
JP2018504234A (ja) 2018-02-15

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